{* ../../docs_src/header_param_models/tutorial001_an_py310.py hl[9:14,18] *}

**FastAPI** will **extract** the data for **each field** from the **headers** in the request and give you the Pydantic model you defined.

## Check the Docs { #check-the-docs }

You can see the required headers in the docs UI at `/docs`:

<div class="screenshot">

     * #COMPLETED}, {@link #CANCELLED}, or {@link #INTERRUPTED}
     *
     * <p>To avoid races between threads doing release and acquire, we transition to the final state
     * in two steps. One thread will successfully CAS from RUNNING to COMPLETING, that thread will
     * then set the result of the computation, and only then transition to COMPLETED, CANCELLED, or
     * INTERRUPTED.
     *

Escribes Python estándar con tipos:

```Python
from datetime import date

from pydantic import BaseModel

# Declara una variable como un str
# y obtiene soporte del editor dentro de la función
def main(user_id: str):
    return user_id


# Un modelo de Pydantic

- ValidatingAdmissionPolicy now exclude TokenReview, SelfSubjectReview, LocalSubjectAccessReview, and SubjectAccessReview from all versions of authentication.k8s.io and authorization.k8s.io group. ([#1235...

	// This is a divergence from S3 limit on purpose to support
	// use cases where users are going to upload large files
	// using 'curl' and presigned URL.
	globalMaxObjectSize = 5 * humanize.TiByte

	// Minimum Part size for multipart upload is 5MiB
	globalMinPartSize = 5 * humanize.MiByte

	// Maximum Part ID for multipart upload is 10000
	// (Acceptable values range from 1 to 10000 inclusive)
	globalMaxPartID = 10000

        // page navi
        RenderDataUtil.register(data, "synonymItemItems", synonymService.getSynonymList(form.dictId, synonymPager));

        // restore from pager
        BeanUtil.copyBeanToBean(synonymPager, form, op -> {
            op.exclude(Constants.PAGER_CONVERSION_RULE);
        });
    }

    // Confirm we enumerate both proxies, giving preference to the route from ProxyB.
    val selection2 = routeSelector.next()
    dns.assertRequests(PROXY_A_HOST, PROXY_B_HOST)
    assertRoute(selection2.next(), address, proxyB, dns.lookup(PROXY_B_HOST, 0), PROXY_B_PORT)
    assertThat(selection2.hasNext()).isFalse()

    // Confirm the last selection contains the postponed route from ProxyA.
    val selection3 = routeSelector.next()

     */
    protected String getVirtualHostBasePath(final String s, final HtmlNext page) {
        return StringUtil.isBlank(s) ? StringUtil.EMPTY : "/" + s;
    }

    /**
     * Gets the virtual host key from the current request.
     * The key is determined by matching HTTP headers against configured virtual hosts.
     *
     * @return The virtual host key, or empty string if no match found
     */

      }
    }
  }

  companion object {
    val playProviderFactory: DeferredSocketAdapter.Factory =
      factory("com.google.android.gms.org.conscrypt")

    /**
     * Builds a SocketAdapter from an observed implementation class, by grabbing the Class
     * reference to perform reflection on at runtime.
     *
     * @param actualSSLSocketClass the runtime class of Conscrypt class socket.
     */

   * types (or if the type is a non-variable type, like {@code String}), then code should almost
   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the